Starting sometime in the mid-'00s it became common practice to prevent players from gratuitously killing child NPCs. As I understand it, this was to comply with

Starting sometime in the mid-'00s it became common practice to prevent players from gratuitously killing child NPCs. As I understand it, this was to comply with ratings boards. A good example of the change is Fallout. Fallout 2 had child NPCs with no invincibility, and in the German release they just made the children invisible and untargetable. This caused some issues. In Fallout 3 children can't be damaged by the player, but you can cause their offscreen deaths (with a nuclear bomb, even). Similarly, I think Crusader Kings can get away with it because there's no visual depiction. As an aside, while I understand the motivation for this kind of thing, I remember finding a child's body after a firefight in Deus Ex and having a moment of moral anxiety as I wondered whether it had been one of my stray bullets or someone else's (or even unrelated to the fight).